Triple-${\bf Q}$ collinear state with compensated ferrimagnetic nature on frustrated kagome lattice

TL;DR

The paper predicts a triple-Q 12-sublattice state in a kagome antiferromagnet that exhibits spin splitting without net magnetization, enabling new spintronics functionalities.

Contribution

It demonstrates that spin-selective band splitting can occur in a symmetric kagome antiferromagnet without crystal asymmetry, due to a unique triple-Q magnetic state.

Findings

Realization of spin splitting in a symmetric kagome antiferromagnet.

Fully compensated ferrimagnetic pattern in local magnetization.

Potential for zero-field spin Seebeck effect and polarized states in metals.

Abstract

Spin-selective band splitting without net magnetization and spin-orbit couplings serves for a next-generation spin-current generator, and its typical platforms are altermagnets and compensated ferrimagnets as well, where the existence of a crystal asymmetry or nonequivalent sites is essential. Here, we theoretically demonstrate that such a splitting can be realized in a triple-{\bf Q} 12-sublattice state emerging in a $J_3$-dominant kagome antiferromagnet, without the help of the crystal asymmetry. Reflecting the multi-sublattice nature, a local magnetization reveals a fully compensated ferrimagnetic pattern in units of a triangle plaquette, leading to $s$-wave-type spin splittings in magnon and electron bands. This enables an atiferromagnetic spin Seebeck effect at zero field in insulating systems and filling-controlled polarized states in metallic systems, highlighting the potential of frustrated magnets to realize novel spintronics functionalities.